On separate acromion process : with appendix on sub-coracoid dislocation of the humerus / by John Struthers.

  • Struthers, John, 1823-1899.
Date:
1896
Catalogue details

Licence: Public Domain Mark

Credit: On separate acromion process : with appendix on sub-coracoid dislocation of the humerus / by John Struthers. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    Normally the facet has an average length of f inch; depth about half the length ; form elliptical, lower edge generally the least bent; surface nearly plane, but usually a little concave both ways. The end of the clavicle has its curves the reverse, but it is often irregular. (d.) Adaptations of the joint.—In direction, autero-posteriorly, the acromio-clavicular joint is nearly at right angles to the axis of the outer part of the clavicle, the direction of which is outwards and a little forwards, and the line of the joint is directly intersected by the line of the bundles of the superior ligament. The clavicle thus, in the antero-posterior direction, abuts directly against the acromion. Vertically, the oblique cutting, downwards and inwards, is, in some of the cases of separate epi-acromion noted below, very little, but is usually marked. This oblique cutting is supposed to be an adaptation to prevent the displacement upwards of the scapula during force from below. The adaptation would be more correctly expressed by saying that, as the plane of the acromion is oblique downwards and outwards, the slant at the joint brings the acromion more directly against the clavicle, thereby giving it a better pivot of support to move on, than if the intersection had been vertical. The obliquity of the intersection is, however, generally greater than is required to make it rectangular to the acromial plane, and will, so far, correct the tendency there would have been for the acromion to be displaced upwards if the intersection had been vertical. Antero-posterior gliding at the joint will tend to obviate shock more than the verti- cal-gliding will. Both are soon checked by the ligaments, mainly by the coraco-clavicular. (e.) The inter-articular fibro-cartilage, partial or complete, that used to be described at the acromio-clavicular articulation as a further provision for obviating shock, I find to be rarely present. Though I have often looked for it, I have only once in my dissect- ing-room experience met with a fibro-cartilage here with complete synovial cavity on each side. That was in Case No. 4, noted below. Nor does a partial wedge-shaped fibro-cartilage occur often, such as that noted below in Case No. 3, best marked on the right side. There are often, indeed generally, synovial fringes projecting into the joint, especially hanging into it from the superior ligament, which probably have been taken for a partial fibro-cartilage. But when the latter occurs its cartilaginous nature is evident. (/.) Various forms of the Acromion Process.—The general form of the acromion in cases of separate epi-acromion appears frequently to be unusual. Irrespective of that condition, the acromion varies much in form, but, for description, four types may be defined, between which there are intermediate forms. Figs. 10 to 13 show these four types diagrammatically, arranged in the order of frequency. The equal frames, with equal subdivisions, enclosing or intersecting the figures, will assist the eye in recognising the